1. Field of the Invention
The present invention relates to a method and device for recording and reproducing information utilizing a work function variation of a recording medium to record information, and a photoelectric or thermoelectric effect to reproduce information, and the
2. Description of the Prior Art
Several conventional methods have been used for recording and reproducing information:
one method for magnetically recording and reproducing information calls for having portions being locally magnetized in a predetermined direction on a magnetic recording medium formed by means of a magnetic head to record information, the information is then reproduced by detecting an arrangement pattern in the magnetized direction using of the magnetic head. PA1 another method for optically recording and reproducing information uses a pit pattern having microscopic unevenness formed on the surface of a recording medium to record information, The information is reproduced by applying a light beam onto the surface of the recording medium and detecting the pit pattern based on the intensity of the reflected light. PA1 yet another method for magneto-optically recording and reproducing information uses heat generated by applying a light beam onto a magneto-optic recording medium to which a magnetic field is being applied, which functions to locally lower coercivity of the medium whereby portions being magnetized in a predetermined direction are formed on the basis of the magnetic field to record information, The information is reproduced by applying a light beam onto the magneto-optic recording medium and then detecting the arrangement pattern in the magnetized direction on the basis of the difference in the angle of the oscillating axis, for example, Kerr effect of the reflected light.
Unfortunately, many drawbacks are associated with using the conventional methods mentioned above. The method for magneto-optically recording and reproducing information, for example, requires a specific magnetic material having a low coercivity and a high residual magnetic flux density and at the same time a low thermal conductivity for the magneto-optic recording medium. Accordingly, a shortcoming exists in that materials suitable for the recording medium are considerably limited. Further, when information is reproduced, the magnetic method requires a magnetism to electric current conversion, the optical method requires a light to electric current conversion, and the magneto-optical method requires a light to electric current conversion. Therefore, processing of regenerative signals becomes complicated thereby suffering from noise influence.
There is another known recording method in which a particle beam is irradiated onto a recording medium to implant or stick the particle (element) thereof to the recording medium for generating a composition change thereof, whereby recording can be performed (refer to Japanese Unexamined Patent Application No. SHO 58(1983)-222453).
However, in order to erase information recorded by utilizing the composition change in such a method, it is necessary to etch the surface of the recording medium by applying an electron, ion, or neutral particle beam thereto, to sputter-etch the overall surface thereof for restoring the original composition state, or to heat the recording medium to evaporate the particle stuck to surface thereof or to diffuse it. This method has a in that the recording medium will deteriorate by repeatedly performing the recording-erasing process.